The field of the invention is generally that of a duplicating machine in which a master sheet is carried on a drum and an impression roll presses copy sheets against the master sheet as the drum is rotated. In the use of the machine, the copy sheets are stacked on a feed table at the inlet of the machine and are fed from it successively to the drum in synchronism with rotation of the drum, one sheet being fed during each revolution of the drum.
When the last copy sheet is fed from the stack, the machine stops. It is important when it stops that the end of the master sheet is beyond, and free of, the impression roll. Otherwise, if the drum remains stopped for any length of time with the master sheet pressed against the drum, the master sheet will have a flaw under the impression roll and this will show on subsequent copies made from that master.
The head or leading end of the master sheet is held by a clamp bar in an axially extending groove formed in the drum with the end of the master sheet beyond the impression roll as described above, the clamp bar should be readily accessible to facilitate changing the master sheet.
Thus, two things are important when the drum automatically stops at the end of a printing run:
1. The end of the master sheet should be beyond the impression roll in case the master sheet is to be reused; and PA1 2. The clamp bar should be accessible, at least for the 11" master sheets most commonly used, in case the master sheet is to be changed.